Research is proposed in the following areas: 1. Thermodynamic and kinetic studies will be carried out of the interactions of anti-cancer drugs with tubulin, and their effects on the modes of tubulin self-assembly will be examined in detail, with particular attention on key chemical groups on the drugs and on entropic effects. 2. The effect of ligands and non-tubulin proteins on tubulin assembly into microtubules and other structures, as well as on tubulin-anti-cancer drugs will be examined. 3. The nature of interactions of solvent components with tubulin will be examined thermodynamically to arrive at an understanding of the mechanism by which they boost microtubule self-assembly.